He was the maternal great-uncle of Prince Philip, Duke of Edinburgh, through his eldest sister, Princess Victoria of Hesse and by Rhine.

[1][2] His siblings included Viktoria, Elisabeth, Irene, Ernst Ludwig, Alix and Marie of Hesse and by Rhine.

Through his eldest sister Viktoria, Friedrich was maternal grand-uncle of Prince Philip, Duke of Edinburgh[3] and through his younger sister Alix, he was maternal uncle of the last four Grand Duchesses Olga, Tatiana, Maria, Anastasia and Alexei Nikolaevich, Tsarevich of Russia.

Ernst ran to another room, which was set at right angles to Alice's bedroom and peered through the window at his younger brother.

[5] Following Friedrich's death, his distraught mother often prayed at his grave and marked anniversaries of small events in his life.